Recently, in semiconductor manufacturing plants, semiconductor wafers are conveyed between each manufacturing apparatus while being stored in semiconductor containers (hereinafter, referred to as a container) with a lid that isolates the semiconductor wafers from the outer environment. The inside of the container is kept in a very clean condition in comparison to the outside and only a small number of foreign particles are adhered to the wafer inside the container if the lid of the container is not opened. The condition outside the container is the ISO cleanliness level 6 or the like, and if the wafer is left in such a condition, over time the foreign particles are adhered to a surface of the wafer. Consequently, the yield of a semiconductor component formed on the wafer is significantly decreased. The container opening/closing apparatus is provided in each manufacturing apparatus, and the inside of the manufacturing apparatus is kept in a very clean condition in comparison to the outside, that is, the ISO cleanliness level 1 to 2.
When the wafer is conveyed from the container to the manufacturing apparatus or from the manufacturing apparatus to the container, the manufacturing apparatus and the container are first connected to each other via the container opening/closing apparatus. Next, the lid of the container is opened, and thereby it is possible to directly connect the clean area inside the manufacturing apparatus and the clean area inside the container. Therefore, there is little possibility that the wafer is exposed to the outside air.
The velocity of opening the lid of the container in the conventional container opening/closing apparatus is set high in order to reduce the operating time. Also, the conventional container opening/closing apparatus is provided with a safety cover that covers a driving system in the rear side of the apparatus. As a result, the lower end portion of this safety cover has a closed structure.
Conventional container opening/closing apparatuses have suffered from the following problem. That is, since the velocity of opening the lid of the container is high, the inside of the container is under negative pressure at the time of opening the lid of the container. As a result, foreign particles outside the container enter the container through the gap between the container and the container opening/closing apparatus, and the foreign particles adhere to the wafer.
In addition, another problem also exists in the conventional container opening/closing apparatus. That is, since a safety cover is provided for the conventional container opening/closing apparatus to cover the driving system in the rear side thereof, and since the lower end portion of the safety cover has a closed structure, foreign particles are deposited inside the safety cover. These foreign particles are blown out when a lid elevator unit moves downward, and then enter the container to adhere to the wafer.
An object of the present invention is to reduce the number of foreign particles adhering to a wafer by preventing the foreign particles from entering the container at the time of opening the container using the container opening/closing apparatus.
Also, another object of the present invention is to reduce the number of foreign particles adhering to a wafer by preventing the foreign particles from being deposited inside the safety cover and preventing the foreign particles from being blown out.